1. Field of the Invention
The present invention relates to a wafer carrying apparatus or cassette, and more particularly, a wafer carrying apparatus or cassette which carry wafers in a semiconductor production line and to which a binding or retention unit is fixed, so as to prevent the wafers from inadvertent egress/exit and being subsequently damaged by a crash, and so on. More specifically, embodiments of the present invention pertain to methods and systems for securing wafers in a wafer cassette in order to prevent wafer loss and/or damage.
2. Discussion of the Related Art
Generally, a wafer carrying apparatus (or cassette) is provided with an opening, an insertion hole (e.g., a plurality of grooves), and a grip or handle. The opening is formed on a front surface of the apparatus to take wafers in and out. The insertion hole(s) are formed at an inner side of the apparatus to keep or support the wafers, and the grip is formed on the top of the cassette or carrying apparatus to carry the wafers. However, since the opening is not provided with any safety unit or wafer retaining mechanism, the apparatus is exposed to a risk that the wafers may fall or be ejected from the apparatus by a collision between workers, an inadvertent impact of the apparatus with a piece of equipment, etc., thereby causing a crash.
For example, in many semiconductor manufacturing and/or test operations, semiconductor wafers are accessed from a wafer cassette that can fit within a pod. Referring now to FIG. 1A, a front view diagram showing a conventional wafer cassette is indicated by the general reference character 100. Cassette handle 102 can be used to carry or move wafer cassette 100. Wafers 104 can be accessed by wafer processing equipment from the front side of wafer cassette 100. Each of the wafers 104 can rest on one or more of fingers 106. Each finger 106 can be separated from the others by an air gap 108.
Referring now to FIG. 1B, a front view diagram showing the conventional wafer cassette of FIG. 1A in a conventional pod is indicated by the general reference character 150. Pod 150 is a standardized piece of equipment for loading and unloading a cassette containing a wafer lot (e.g., a group of 24 or 25 wafers) into and out of semiconductor processing equipment, such as an etcher, a plasma deposition apparatus, a photolithography apparatus, cleaning equipment, a tester, etc. While in the pod, wafers 104 cannot be accessed. Wafer cassette 100 must be removed from the pod and then wafers 104 can be accessed from one side of wafer cassette 100. However, wafers 104 are susceptible to either partially or fully falling out of wafer cassette 100 during a transition between pod 150 and manufacturing and/or test equipment. Accordingly, wafers 104 may be damaged by wafer movement in the direction of the open or accessible side of wafer cassette 100.
To solve such a problem, a wafer carrying apparatus has been suggested in the Korean Registered Utility Model No. 121642 as shown in FIG. 2. The apparatus includes insertion holes 209 formed at lower and upper portions in an insertion direction of a side plate 208, binding rings 10 rotatably provided in the insertion holes 209 to be selectively positioned at inner and outer sides of the side plate, a release groove 211 and a control groove 212 formed to communicate with the insertion holes 209, inserting a lower end portion of the binding rings 210, and a spring provided in the upper insertion hole of the insertion holes 209 to upwardly push the binding rings.
However, the aforementioned wafer carrying apparatus has several problems.
Although the apparatus prevents the wafers from being detached or ejected therefrom, the fabricating cost is high because of a complicated structure. Also, to use the apparatus, complicated operations are separately required in such a manner that the binding rings 210 are inserted into the control groove 212 after they are moved to the insertion holes 209 and rotated.